The present invention relates in general to automotive HVAC systems, and, more specifically, to automatic adjustment of steerable air outlets to direct treated air to optimize passenger comfort and reduce energy usage.
Heating, ventilating, and air conditioning (HVAC) systems control the climate in transportation vehicles such as automobiles in order to maintain thermal comfort of the vehicle occupants. Typically, a blower passes air through heat exchangers and delivers conditioned air to various points within the passenger cabin. Warm air may be provided by a heater core obtaining heat from coolant flowing in a combustion engine, for example. Cool air may be obtained using a compressor mechanically-driven by the engine. Electrified vehicles such as hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs) may instead use electrically powered devices such as PTC resistance heaters and electric air conditioning compressors.
The simplest climate control systems in motor vehicles provide the occupant with direct control of the intensity of heating or cooling, the operating speed of the blower, and the relative amount of air flow going to different registers. This requires the user to continually monitor and adjust the climate control settings in order to remain comfortable. The vehicle occupants, however, may not understand how to best control the HVAC system to optimize efficiency. They may turn the control knobs to a maximum output while aiming the blower vanes upward or downward away from their bodies, sending the conditioned air tumbling onto less important surfaces and requiring more energy to make the occupants comfortable. This also results in greater blower fan noise than is really necessary to achieve the desired thermal comfort.
Electronic automatic temperature control (EATC) systems have also been introduced wherein a feedback control system monitors ambient air temperature within the passenger compartment and automatically adjusts blower speed and heater core or air conditioning operation to maintain a desired temperature setting. In some vehicles, multiple zones have been implemented with separate automatic temperature control with individual target temperature settings being made for each zone.
Traditional HVAC systems only indirectly control the actual skin temperature of an occupant. Because skin temperature is a better indicator of actual occupant comfort, systems have been investigated for regulating HVAC system operation using infrared (IR) sensors to determine the skin temperature of the vehicle occupants and then adjusting a temperature setpoint of the HVAC system in the direction required to achieve a target skin temperature. However, the thermodynamic environment in a vehicle interior is complex, as are the relationships between various HVAC control settings and the resulting effect on skin temperature of different occupants. Therefore, previous systems have been relatively complex and not cost effective.
In order to reduce energy consumption and to provide optimal comfort, various systems have also been proposed which automatically adjust the pattern of air flow delivered into the passenger compartment based upon seat occupancy (e.g., turning off vents where a seat is unoccupied). However, no known system has provided sufficient accuracy or performance to truly optimize directional adjustment of treated air over a sufficiently wide range of thermal conditions.